Why drywall joint cracks and how Liagle Tapeless Drywall Finishing works
Part 2 :
Reasons for drywall joint cracks and how fibre reinforced drywall mud works
Part 3 :
Reasons for ceiling joint cracks and how fibre reinforced drywall mud works
Building shifting, temperature and moisture changes, even wind blow on a house cause stresses to drywall joints. Crack happens if the joints are not strong enough to resist the stresses. There are mainly two reasons for drywall joint cracking:
First, drywall boarding issues.
Second, drywall taping problems.
Most of cracks occurred on the joints above windows and doors.
Try your best To avoid joints around high stress areas.
The worst is joint right on the corner above windows and doors!
A common mistake for drywall boarding is to line up the joints. Especially on ceilings. Avoid to line up butt joints on walls as well.
Most of ceiling joint cracks are around load bearing wall. Especially on corners.
Lack of backing is a common reason cause joint crack. Joint is on the very edge of studs or ceiling joist. Screws on the very edge of the drywall sheet can not fasten drywall to the studs or joist properly.
Cracks on ceiling joints often caused by drywall sagging. Especially flat joint along ceiling joist without enough screws.
Cut the cracked joints open, almost 100% of them, there was no mud filled in the joint gaps. It is most common reason for drywall joint crack.
Using bazooka or banjo box to apply paper tape, there is only a thin layer of mud in the back of the tape. There is no mud in joint gaps.
Without pre-fill, even using mesh tape, the cavity in the joint is not filled with mud.
Because there is no mud filled in the gap, only a layer of paper tape could not resist the stress on the joint, that was why the joint cracked.
Without pre-fill, even mesh tape with fast set mud cracks.
There is plastic shrinkage when temperature and moisture change. If the layer of mud on top of the tape is too thick, we have very good chance to have a crack.
When the joint is filled with mud, the two sheets of drywall are welded in to one piece. The joint is stronger than just a piece of paper tape covering the joint with a hollowing cavity in the back.
Unfortunately, some tapers skip the process of pre-fill for some reasons.
For more information about how to install drywall: